.central-game-area { display: flex; flex-direction: column; justify-content: center; min-height: 250px; margin-top: 20px; }
.juego { text-align: center; padding: 10px; }
.start-container { display: flex; flex-direction: column; align-items: center; justify-content: center; gap: 15px; padding: 20px; }
.start-button { background-color: #1978a1; color: white; border: none; padding: 20px 40px; font-size: 2.7em; cursor: pointer; border-radius: 8px; font-weight: bold; margin: 0; line-height: 1; transition: background-color 0.2s, transform 0.1s; }
.start-button:hover { background-color: #146080; transform: scale(1.05); }
.start-button:disabled { background-color: #ccc; cursor: not-allowed; transform: none; }
.hidden { display: none !important; }
.cifras-board { margin: 0 auto; background: #eee; padding: 15px; border-radius: 10px; border: 1px solid #ddd; }
.screen-area { background: #333; color: #ffff00; padding: 15px; border-radius: 8px; margin-bottom: 10px; display: flex; justify-content: space-between; align-items: center; border: 4px solid #555; }
.target-number { font-size: 2.5em; font-weight: bold; font-family: 'Courier New', monospace; letter-spacing: 2px; }
.timer-display { font-size: 1.5em; color: white; font-family: sans-serif; background: #d00; padding: 5px 10px; border-radius: 4px; min-width: 60px; text-align: center; }
.tiles-area { display: flex; justify-content: center; flex-wrap: wrap; gap: 10px; margin-bottom: 20px; align-items: center; }
.start-area { display: flex; flex-direction: column; align-items: center; gap: 20px; margin-bottom: 20px; }
.buttons-container { display: flex; justify-content: center; gap: 20px; flex-wrap: wrap; }
.common-description { max-width: 600px; background: #eaeaea; padding: 15px; border-radius: 5px; box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1); color: #444; line-height: 1.5; text-align: left; width: 90%; }
.common-description p { margin: 5px 0; }
.letra-tile { width: 60px; height: 60px; background: linear-gradient(180deg, #3377ff 0%, #2255dd 100%); color: white; font-size: 1.4em; font-weight: bold; border: 2px solid #003399; border-radius: 5px; display: flex; align-items: center; justify-content: center; box-shadow: 0 3px 5px rgba(0, 0, 0, 0.2); cursor: pointer; text-transform: uppercase; }
.letra-tile.used { background: #ccc; color: #777; border-color: #999; cursor: default; box-shadow: inset 0 0 5px rgba(0, 0, 0, 0.1); transform: none !important; }
.result-letter { font-size: 2em; font-weight: bold; color: #1978a1; cursor: pointer; margin: 0 1px; line-height: 1; user-select: none; }
.result-letter:hover { color: #d9534f; }
.letras-input-area { display: flex; flex-direction: column; align-items: center; gap: 15px; width: 100%; justify-content: flex-start; margin-bottom: 20px; }
#letrasResultContainer { display: flex; justify-content: center; flex-wrap: wrap; gap: 10px; width: 100%; margin-bottom: 20px; }
#userWordInput { padding: 10px; font-size: 1.5em; width: 80%; max-width: 300px; text-align: center; text-transform: uppercase; border: 2px solid #ccc; border-radius: 5px; font-family: monospace; letter-spacing: 3px; background-color: #fff; color: #333; }
.tile { width: 60px; height: 60px; background: linear-gradient(180deg, #3377ff 0%, #2255dd 100%); color: white; font-size: 1.4em; font-weight: bold; border: 2px solid #003399; border-radius: 8px; display: flex; align-items: center; justify-content: center; cursor: pointer; user-select: none; box-shadow: 0 3px 5px rgba(0, 0, 0, 0.2); transition: transform 0.1s; line-height: 1; padding-bottom: 2px; }
.tile:active { transform: translateY(2px); }
.tile.new-tile { animation: popIn 0.6s cubic-bezier(0.175, 0.885, 0.32, 1.275); border-color: #ffd700; z-index: 10; }
@keyframes popIn { 0% { transform: scale(0.5); opacity: 0; } 100% { transform: scale(1); opacity: 1; } }
.tile.selected { background: #ff9900; border-color: #cc7a00; transform: scale(1.1); box-shadow: 0 0 10px #ff9900; }
.tile.used { opacity: 0; pointer-events: none; cursor: default; }
.operators-area { display: flex; justify-content: center; gap: 15px; margin-bottom: 20px; }
.operator-btn { width: 50px; height: 50px; background: #fff; color: #333; font-size: 1.5em; font-weight: bold; border: 2px solid #ccc; border-radius: 50%; cursor: pointer; }
.operator-btn.selected { background: #ff9900; color: white; border-color: #e68a00; }
.history-container { background: white; border: 1px solid #ccc; padding: 10px; text-align: left; margin-bottom: 20px; border-radius: 5px; font-family: monospace; font-size: 1.1em; }
.history-line { border-bottom: 1px solid #eee; padding: 4px 0; }
.game-controls { display: flex; justify-content: center; gap: 10px; }
.btn-control { padding: 8px 15px; font-size: 1.3em; border: none; border-radius: 4px; cursor: pointer; color: white; font-weight: bold; }
.btn-undo { background-color: #f0ad4e; }
.btn-reset { background-color: #d9534f; }
.btn-check { background-color: #5cb85c; }
.msg-box { font-weight: bold; padding: 5px; color: #333; text-align: center; display: block; line-height: 1.3; margin-bottom: 20px; width: 100%; }
.msg-box strong { display: inline !important; }
.success-msg { color: #28a745; }
.error-msg { color: #d9534f; }

@media(max-width: 500px) {
    .tile { width: 42px; height: 42px; font-size: 1em; margin: 1px; }
    .letra-tile { width: 50px; height: 50px; font-size: 1em; margin: 1px; }
    .tiles-area, #letrasResultContainer { gap: 4px; }
    .operator-btn { width: 40px; height: 40px; }
    .target-number { font-size: 2em; }
    .start-button { font-size: 1.5em; padding: 12px 20px; }
}

@media(max-width: 450px) {
    .btn-control { padding: 6px 10px; }
    .start-button { max-width: 230px !important; }
}